"The increase in strength of Boko Haram reflects our slowness and our inability to put up a robust response," Niger's Foreign Minister Mohamed Bazoum said at the talks in Niamey.
"We are watching, as was the case in Mali, the loss of sovereignty in Nigeria over large tracts of its territory and the exporting of the violence to neighbouring countries."
Ministers from Nigeria, Cameroon, Chad, Niger, Benin, Equatorial Guinea were due to attend, along with representatives from the US, the European Union, China and several other countries.
Chad sent on Saturday a convoy of troops and 400 military vehicles into neighbouring Cameroon to fight Boko Haram, with Nigeria's army widely criticised for failing to crush the militants.
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A Boko Haram assault this month on the town of Baga on the shores of Lake Chad trigged widespread outrage and helped spur a regional response.
Amnesty International described the attack, which is believed to have killed hundreds of people, as "the biggest and most destructive" yet by the armed fundamentalists.
Cameroon has also seen repeated attacks recently, including the kidnapping of dozens of people, mostly women and children, during a deadly attack on Sunday.
"The security situation in Nigeria and in the Lake Chad basin has deteriorated considerably," Bazoum told the Niamey meeting, adding that the fall of Baga showed that the sect has "more and more substantial resources" in firepower.
Chad's President Idriss Deby, who backs a regional effort, last week announced his determination to recapture Baga, a strategic area on Lake Chad where the borders of Chad, Cameroon, Niger and Nigeria converge.
However, Cameroon's Communications Minister Issa Tchiroma Bakary said it would take time to coordinate Cameroonian and Chadian troops.